<p>Today I came across term <a href="https://martinfowler.com/bliki/BlueGreenDeployment.html">Blue-Green deployment</a> while reading through some articles and this is a perfect <abbr title="Today I learned">TIL</abbr>.</p>
<h2>What is it?</h2>
<p>In a nutshell, Blue-Green Deployment is a technique of running two identical production environments called Blue and Green.</p>
<p>At any time, only one of the environments is live, with the live environment serving all production traffic.</p>
<p>For e.g - let say we have the Blue environment currently live. As we prepare a new version of software, the deployment and final stage of testing takes place in the environment that is not live: in this example, Green.</p>
<p>Once we have deployed and fully tested the software in Green, we switch the router so all incoming requests now go to Green instead of Blue.</p>
<p>Green is now live, and Blue is idle.</p>
<h2>Advantages</h2>
<p>This technique can eliminate downtime due to app deployment.</p>
<p>In addition, blue-green deployment reduces risk: if something unexpected happens with the new version on Green, we can immediately roll back to the last version by switching back to Blue.</p>
<h2>References</h2>
<ul>
<li><a href="https://martinfowler.com/bliki/BlueGreenDeployment.html">Martin Fowler article on Blue-Green deployment</a></li>
<li><a href="https://docs.cloudfoundry.org/devguide/deploy-apps/blue-green.html">Cloud foundary guide on Blue-Green deployment</a></li>
<li><a href="https://opensource.com/article/17/5/colorful-deployments">Article on colorful deployments</a></li>
</ul>
